The present invention is generally directed to integrated circuit (IC) packages and, more specifically, to an IC device which exposes the upper and lower surfaces of the integrated circuit die.
The size of integrated circuit (IC) packages continues to decrease even as the complexity and level of circuit integration in the IC packages continue to increase. This is particularly true in the case of system-on-a-chip (SoC) devices, in which most, if not all, of an electronic appliance is integrated onto a single integrated circuit die. Thus, relatively complex devices, such as cell phones, network interface cards (NICs), communication buses, and the like, are now being implemented as a single integrated circuit or perhaps only several integrated circuits.
Many integrated circuit (IC) devices do not encapsulate the entire IC chip in a protective package. For example, an IC sensor chip used in a fingerprint reader is a Touch-chip(trademark) device (produced by STMicroelectronics, Inc.) that uses a sensor array to read a fingerprint. In order to work properly, the sensor array must be at least partially exposed in order to receive the finger of a user. Other types of IC packages that expose the surface of the integrated circuit are chemical and pressure sensors. Optical sensors may be covered by a lens element. Light sensitive elements on the surface of the IC die are left exposed in order to detect light. More generally, it is useful in many applications to leave at least a portion of the surface of an IC die exposed so that test points on the IC die may be probed. Alternatively, it may be useful to leave a portion of the IC die surface exposed so that an end-user of the IC device may incorporate the IC package into a larger system by forming electrical connections to points on the surface of the IC die selected by the end-user, rather than the manufacturer of the IC package.
For these types of devices, it is necessary to package the IC die in such a way that the edges and wires of the IC die are protected, but the sensor array and/or test points on the surface or the IC die remain completely exposed. The packaging is usually accomplished using some kind of molding process. However, this process is made more difficult by the need to prevent molding flash from forming on the IC sensor and by the need to compensate for variation in die thickness and die tilt. The exposed IC sensor surface is brittle and must be handled carefully to prevent it from shattering during the manufacturing process and in the field.
Also, these sensors are generally integrated into a hand-held device, such as a mobile phone to check fingerprints, a portable glucose meter to check the composition of body fluids, or a web-cam to take a picture. The packaging of these sensors has to be very efficient, to make the sensor very adaptable for integration into a hand-held system using a conventional surface mount (soldering) process. The smallest possible package is the silicon sensor itself, without the packaging. However, this is not compatible with the surface mounting process. Standard packages, such as Dual-in-Line package (DIP) or Quad Flat Pack (QPF), increase the mounting areas because of their leads. Other packages, such as BGA, add an excessive amount of additional thickness to the sensor.
Therefore, there is a need in the art for improving the packaging of an IC sensor that contains at least a partially exposed integrated circuit die surface.
To address the above-discussed deficiencies of the prior art, it is a primary object of an advantageous embodiment of the present invention to provide an integrated circuit (IC) device comprising: 1) an integrated circuit (IC) die having a first surface, a second surface opposite the first surface, and sidewalls extending between the first surface and the second surface; and 2) an integrated circuit (IC) package for supporting the IC die, wherein the IC package is attached to at least one of the sidewalls of the IC die such that at least a portion of the IC die first surface and at least a portion of the IC die second surface are exposed.
According to one embodiment of the present invention, the IC package has a first surface and a second surface opposite the IC package first surface, and wherein the IC package second surface lies in substantially the same plane as the IC die second surface.
According to another embodiment of the present invention, a first portion of the IC package is attached to and covers at least part of a peripheral portion of the IC die first surface.
According to still another embodiment of the present invention, the IC package encases at least one electrical connection extending between a contact pad on the peripheral portion of the IC die first surface and a contact pad disposed on the IC package second surface.
According to yet another embodiment of the present invention, an exposed surface of the contact pad disposed on the IC package second surface lies in substantially the same plane as IC die second surface.
According to a further embodiment of the present invention, an exposed surface of the contact pad disposed on the IC package second surface is recessed in an indentation in the IC package second surface.
According to a still further embodiment of the present invention, substantially all of the IC die second surface is exposed.
According to a yet further embodiment of the present invention, the IC die second surface is suitable for attachment to a heat sink.
In one embodiment of the present invention, the IC die second surface is suitable for attachment to a ground plane contact of a printed circuit board.
In another embodiment of the present invention, at least one of the IC die first surface and the IC die second surface have exposed test points thereon.
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms xe2x80x9cincludexe2x80x9d and xe2x80x9ccomprise,xe2x80x9d as well as derivatives thereof, mean inclusion without limitation; the term xe2x80x9cor,xe2x80x9d is inclusive, meaning and/or; the phrases xe2x80x9cassociated withxe2x80x9d and xe2x80x9cassociated therewith,xe2x80x9d as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term xe2x80x9ccontrollerxe2x80x9d means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. In particular, a controller may comprise a data processor and an associated memory that stores instructions that may be executed by the data processor. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.